Refrigeration machine

ABSTRACT

Provided is a refrigeration machine having: a refrigeration cycle having a compressor, a condenser, an expander, an evaporator, piping (12) which sequentially connects the compressor, the condenser, the expander, and the evaporator, and discharge piping; and an acoustic device (13) provided to the piping (12). The acoustic device (13) has a space formation section (14) having a space (S) formed therein and also having an open first end (14a) which is connected to the piping (12) so as to be in communication therewith; an extendible and contractible bellows pipe (21) connected to an open second end of the space formation section (14); and a sealing section (20) provided to the end of the bellows pipe (21), which is located on the opposite side thereof from the space formation section (14).

TECHNICAL FIELD

The present invention relates to a chiller.

This application claims the priority of Japanese Patent Application No. 2017-223822 filed in Japan on Nov. 21, 2017, the contents of which are incorporated herein by reference.

BACKGROUND ART

A chiller is a heat source machine that is used widely for applications such as air conditioning of a factory having a clean room such as an electrical and electronic factory, and district cooling and heating. As the chiller, a refrigerator is known in which the components such as a centrifugal compressor, a condenser, and an evaporator are arranged in the vicinity and integrated into a unit (for example, see PTL 1).

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. 2002-327700

SUMMARY OF INVENTION Technical Problem

An increase in noise generated from the chiller has been a problem with an increase in the efficiency of the chiller. The causes of noise generated from the chiller are classified into two types of noise due to mechanical causes and noise due to fluid causes.

The noise due to the mechanical causes is generated by periodic flow fluctuations due to the movement of the blades and the number of diffuser blades generated when the centrifugal compressor or a pump operates. The periodic flow fluctuations cause a pressure pulsation, whereby noise called NZ sound is generated.

The noise due to the mechanical causes has a property of a specific and single frequency characteristic. It has been known that noise due to the mechanical causes resonates with an acoustic eigenvalue of a pipe or the like inside the chiller and the sound is amplified.

An object of the invention is to provide a chiller that includes a refrigeration cycle including a compressor, a condenser, an expander, an evaporator, and a pipe that sequentially connects the compressor, the condenser, the expander, and the evaporator, and is capable of suppressing noise.

Solution to Problem

An aspect of the invention relates to a chiller including a refrigeration cycle including a compressor, a condenser, an expander, an evaporator, a pipe that sequentially connects the compressor, the condenser, the expander, and the evaporator, and a discharge pipe, and an acoustic device provided in the pipe, which the acoustic device includes a space formation section in which a space is formed and which has an open first end connected to the pipe in a communicating state, a bellows pipe that is connected to an open second end of the space formation section and is extendable and contractable, and a sealing section that is provided in an end portion of the bellows pipe on a side opposite to the space formation section.

According to the configuration, by attaching the acoustic device to the pipe, it is possible to reduce noise due to resonance of an acoustic eigenvalue of the space in the pipe with NZ sound of at least one component of the compressor, the condenser, the expander, the evaporator, and the pipe that configure the chiller. The bellows pipe configuring the acoustic device expands to convert the acoustic energy into the structural vibration energy, whereby it is possible to reduce the size of the acoustic device.

In the chiller, the space formation section may include a first tubular section having a cylindrical shape, a second tubular section having a cylindrical shape, and a second bellows pipe connecting the first tubular section to the second tubular section, the first end may be an end portion of the first tubular section on a side opposite to the second bellows pipe, and the second end may be an end portion of the second tubular section on a side opposite to the second bellows pipe.

According to the configuration, it is possible to reduce noise by dividing the bellows pipe without lengthening the bellows pipe.

In the chiller, the space formation section may include a tubular section that has one end portion connected to the pipe in a communicating state, and a container section that has an open first opening connected to the other end portion of the tubular section in a communicating state and has a volume larger than a volume of the space in the tubular section, and the bellows pipe may be connected to an open second opening of the container section.

According to the configuration, the volume of the container section of the acoustic device can be adjusted, whereby the acoustic impedance of the pipe can be adjusted.

In the chiller, the acoustic device may include a porous plate disposed at a boundary between the space formation section and a flow path of the pipe.

According to the configuration, it is possible to suppress generation of the acoustic impedance of a specific frequency of the pipe, which may resonate with the NZ sound of the compressor configuring the chiller. Therefore, it is possible to reduce the noise level.

Advantageous Effects of Invention

According to the invention, by attaching the acoustic device to the pipe, it is possible to reduce noise due to resonance of an acoustic eigenvalue of the space in the pipe with the NZ sound of at least one component of the compressor, the condenser, the expander, the evaporator, and the pipe that configure the chiller. The bellows pipe configuring the acoustic device expands to convert the acoustic energy into the structural vibration energy, whereby it is possible to reduce the size of the acoustic device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration view of a chiller according to a first embodiment of the invention.

FIG. 2 is a schematic configuration view of a compressor, a condenser, and a pipe that connects the compressor, and the condenser of the chiller according to the first embodiment of the invention.

FIG. 3 is a cross-sectional view of an acoustic device of the chiller according to the first embodiment of the invention.

FIG. 4 is a cross-sectional view of an acoustic device of the chiller according to a second embodiment of the invention.

FIG. 5 is a cross-sectional view of an acoustic device of the chiller according to a third embodiment of the invention.

FIG. 6 is a cross-sectional view of an acoustic device of the chiller according to a fourth embodiment of the invention.

FIG. 7 is a cross-sectional view of an acoustic device of the chiller according to a fifth embodiment of the invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinafter, a chiller according to a first embodiment of the invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a chiller 1 of the present embodiment includes a compressor 2 that compresses a refrigerant W, a condenser 3 that condenses the refrigerant W compressed by the compressor 2 by cooling water, a first expansion valve 4 that is an expander depressurizing the refrigerant W from the condenser 3, and an economizer 6 (a gas-liquid separator) that separates the refrigerant W from the first expansion valve 4 into two phases of gas and liquid.

Also, the chiller 1 includes an inflow path 8 that allows a gas phase W1 from the economizer 6 to flow into the compressor 2, a second expansion valve 5 that depressurizes a liquid phase from the economizer 6 again, and an evaporator 7 that evaporates the refrigerant W from the second expansion valve 5.

A hot gas bypass pipe 9 is provided between a gas phase section of the condenser 3 and a gas phase section of the evaporator 7. The hot gas bypass pipe 9 is provided with a hot gas bypass valve 10 for controlling a flow rate of a high-temperature refrigerant gas flowing in the hot gas bypass pipe 9.

The chiller 1 includes a refrigeration cycle 11 including a pipe 12. The pipe 12 sequentially connects the compressor 2, the condenser 3, the first expansion valve 4, the second expansion valve 5, and the evaporator 7. Specifically, the chiller 1 includes a pipe 12 a that connects the compressor 2 and the condenser 3, a pipe 12 b that connects the condenser 3 and the economizer 6, a pipe 12 c that connects the economizer 6 and the evaporator 7, and a pipe 12 d that connects the evaporator 7 and the compressor 2. The pipe 12 is a flow path through which the refrigerant W flows.

The refrigerant W is, for example, R134a of alternative chlorofluorocarbon (hydrofluorocarbons).

An acoustic device 13 that reduces noise generated in the compressor 2 is provided in the pipe 12 a that connects the compressor 2 and the condenser 3.

The compressor 2 is a centrifugal two-stage compressor, and is driven by an electric motor (not shown) of which a rotation speed is controlled by an inverter that changes input frequency from a power supply.

The condenser 3 is a device that cools the refrigerant W compressed by the compressor 2 by exchanging heat with cooling water and makes the refrigerant W to be in a liquid state. The condenser 3 is, for example, a shell and tube type heat exchanger.

The first expansion valve 4 is an expander that adiabatically expands and depressurizes the liquid refrigerant W from the condenser 3, evaporates a part of the liquid, and makes the refrigerant W into two phases of gas and liquid.

The economizer 6 is a device that separates the refrigerant W in a state of two phases of gas and liquid in the first expansion valve 4 into the gas phase W1 and the liquid phase.

The inflow path 8 is a flow path through which the gas phase W1 separated from the refrigerant W of two phases of gas and liquid by the economizer 6 flows into the compressor 2.

The second expansion valve 5 is an expander that adiabatically expands and depressurizes the refrigerant W in which the gas phase W1 is separated by the economizer 6 and only the liquid phase is present, similar to the first expansion valve 4. In the chiller 1 according to the present embodiment, the refrigerant W is depressurized by using the expansion valve, but the configuration is not limited thereto, and the refrigerant W may be depressurized by using other means.

The evaporator 7 evaporates the refrigerant W from the second expansion valve 5 by exchanging heat with water and makes the refrigerant W to be in a saturated vapor state.

As shown in FIG. 2, the acoustic device 13 is a silencer provided in the pipe 12 a that connects the compressor 2 and the condenser 3. The acoustic device 13 includes a cylindrical space formation section 14 that is connected to the pipe 12, a bellows pipe 21 that is connected to the space formation section 14, and a sealing section 20 that seals the end portion of the bellows pipe 21.

When the compressor 2 operates, the periodic flow fluctuation is generated due to the rotation of the impeller or the number of diffuser blades. The periodic flow fluctuations cause a pressure pulsation, whereby noise called NZ sound is generated.

The NZ sound generated due to the mechanical causes has a property of a specific and single frequency characteristic, and may resonate with the acoustic impedance of the pipe 12 of the chiller 1. That is, it is known that the NZ sound is in an acoustic mode M as indicated by a two-dot chain line in FIG. 2 and is amplified.

The acoustic mode M has an antinode M1 and a node M2. The antinode M1 is a position where the acoustic energy (amplitude) is maximum, and the node M2 is a position where the acoustic energy (amplitude) is substantially zero.

The acoustic device 13 is attached to the position of the antinode M1 of the acoustic mode M. Stated another way, the acoustic device 13 is attached to the position where the acoustic energy of sound generated in the pipe 12 is maximum.

As shown in FIG. 3, a space S is formed inside the space formation section 14. The space formation section 14 has an open first end 14 a connected to the pipe 12 in a communicating state. In a word, the space S inside the space formation section 14 communicates with a space inside the pipe 12.

The space formation section 14 includes a cylindrical main body section 16, and a flange section 18 provided in the first end 14 a. The shape of the main body section 16 is not limited thereto, and may be a rectangular tube shape. A center axis As of the acoustic device 13 is substantially orthogonal to a center axis Ad (see FIG. 2) of the pipe 12.

The flange section 18 is formed in the first end 14 a of the main body section 16 so as to project radially outward of the center axis As of the main body section 16. The acoustic device 13 is fixed to the pipe 12 via the flange section 18.

The space formation section 14 is, for example, formed of stainless steel such as SUS316. The material forming the space formation section 14 is not limited to SUS316, and a predetermined metal can be appropriately selected.

The bellows pipe 21 is a bellows-shaped expansion pipe having a cylindrical shape. The bellows pipe 21 is connected to an open second end 14 b of the space formation section 14. The bellows pipe 21 can be formed of, for example, a metal such as stainless steel or aluminum. The bellows pipe 21 may be manufactured by molding a cylindrical metal using a jig, or may be manufactured by welding a plurality of disk-shaped metals to each other.

The sealing section 20 is a plate-shaped member that is provided in an end portion of the bellows pipe 21 on a side opposite to the space formation section 14. The sealing section 20 can be formed of the same metal as the metal forming the space formation section 14. The metal forming the space formation section 14 may be different from the metal, forming the sealing section 20. The shape of the sealing section 20 is not limited to the plate shape, and the sealing section 20 may be, for example, a hemispherical member.

The space formation section 14 and the bellows pipe 21 can be joined to each other by welding. Similarly, the bellows pipe 21 and the sealing section 20 can be joined to each other by welding.

The space formation section 14, the bellows pipe 21, and the sealing section 20 forms a resonance space that is hermetically sealed and reduces sound by interference of sound waves.

According to the embodiment, by attaching the acoustic device 13 to the pipe 12, it is possible to reduce noise due to resonance of the acoustic eigenvalue of the space in the pipe 12 with the NZ sound of the compressor 2 configuring the chiller 1. The bellows pipe 21 forming the resonance space of the acoustic device 13 expands to convert the acoustic energy into the structural vibration energy, whereby it is possible to reduce the size of the acoustic device 13. That is, a projecting amount L of the acoustic device 13 from the pipe 12 can be reduced.

The acoustic device 13 is connected to the pipe 12 via the flange section 18, whereby the acoustic device 13 can be easily replaced and maintained.

In the above embodiment, the acoustic device 13 is installed in the pipe 12 a between the compressor 2 and the condenser 3, but the configuration is not limited thereto. For example, the acoustic device 13 may be disposed in the pipes 12 b and 12 c between the condenser 3 and the evaporator 7, the pipe 12 d between the evaporator 7 and the compressor 2, or the hot gas bypass pipe 9.

The number of acoustic devices 13 is not limited to one. The acoustic device 13 can be attached to at least one of the components (the compressor 2, the condenser 3, the expanders 4 and 5, the evaporator 7, and the pipe 12) that configure the refrigeration cycle 11. For example, the acoustic devices 13 may be attached to all the pipes 12, or two acoustic devices 13 may be attached to one pipe 12.

Also, the acoustic device 13 may be disposed in a discharge pipe through which an unnecessary fluid is discharged.

Second Embodiment

Hereinafter, a chiller according to a second embodiment of the invention will be described in detail with reference to the drawings. In the present embodiment, differences from the first embodiment will be mainly described, and the description of the same parts will be omitted.

As shown in FIG. 4, the sealing section 23 of an acoustic device 13B according to the present embodiment has a bottomed cylindrical shape.

The sealing section 23 according to the present embodiment includes a cylindrical section 23 a having a cylindrical shape, and a disc section 23 b that seals one end of the cylindrical section 23 a. The sealing section 23 and the bellows pipe 21 are connected by joining the end portion of the cylindrical section 23 a and the end portion of the bellows pipe 21.

According to the embodiment, the bellows pipe 21 can be disposed at a position spaced from the end portion of the acoustic device 13B.

Third Embodiment

Hereinafter, a chiller according to a third embodiment of the invention will be described in detail with reference to the drawings. In the present embodiment, differences from the first embodiment will be mainly described, and the description of the same parts will be omitted.

As shown in FIG. 5, a space formation section 14C of an acoustic device 13C according to the present embodiment includes two tubular sections 16 a and 16 b, a second bellows pipe 21C that connects the tubular sections to each other.

The space formation section 14C according to the present embodiment includes the first tubular section 16 a having a cylindrical shape and the second tubular section 16 b having a cylindrical shape. The first tubular section 16 a and the second tubular section 16 b are connected to each other by the second bellows pipe 21C having the same configuration as the bellows pipe 21.

The first end 14 a of the space formation section 14C may be an end portion of the first tubular section 16 a on a side opposite to the second bellows pipe 21C. The second end 14 b of the space formation section 14C may be an end portion of the second tubular section 16 b on a side opposite to the second bellows pipe 21C.

According to the embodiment, it is possible to reduce noise by dividing the bellows pipe into the bellows pipe 21 and the second bellows pipe 21C without lengthening the bellows pipe.

Fourth Embodiment

Hereinafter, a chiller according to a fourth embodiment of the invention will be described in detail with reference to the drawings. In the present embodiment, differences from the first embodiment will be mainly described, and the description of the same parts will be omitted.

As shown in FIG. 6, an acoustic device 13D according to the present embodiment includes a porous plate 15 disposed at a boundary between the first end 14 a of the space formation section 14 and a flow path of the pipe 12.

The porous plate 15 is for suppressing air turbulence at the first end 14 a of the space formation section 14.

The porous plate 15 is provided at the first end 14 a of the space formation section 14. A main surface of the porous plate 15 is substantially orthogonal to the center axis As of the main body section 16. A plurality of circular through-holes 19 are regularly arranged in the porous plate 15. The shape of the through-hole 19 is not limited to a circle, and may be a rectangular or a slit shape.

In the chiller 1 according to the present embodiment, a length L of the acoustic device 13D, a pore diameter ϕ of the through-hole 19 of the porous plate 15, and an opening ratio σ (a ratio of area of through-hole 19 per area of the porous plate 15) of the porous plate 15 are adjusted to make the boundary between the pipe 12 and the condenser 3 to be Z=ρc boundary.

The Z=ρc boundary is a boundary in which an acoustic impedance Z at the boundary is matched to make the reflection of sound non-reflective by using the parameter expressed by the acoustic impedance Z as the density p and a sound velocity c.

According to the above embodiment, it is possible to suppress generation of the acoustic impedance of a specific frequency of the pipe 12, which may resonate with the NZ sound of the compressor 2 configuring the chiller 1. Therefore, it is possible to reduce the noise level.

The acoustic impedance of the pipe 12 can be adjusted by adjusting the length L of the acoustic device 13 (the main body section 16), the pore diameter φ of the through-hole 19 of the porous plate 15, and the opening ratio σ of the porous plate 15.

Fifth Embodiment

Hereinafter, a chiller according to a fifth embodiment of the invention will be described in detail with reference to the drawings. In the present embodiment, differences from the first embodiment will be mainly described, and the description of the same parts will be omitted.

As shown in FIG. 7, the shape of a space formation section 14E of an acoustic device 13E according to the third embodiment is different from the shape of the space formation section of the acoustic device 13 according to the first embodiment. The space formation section 14E according to the present embodiment includes a tubular section 24 and a container section 25.

The tubular section 24 has one end portion 24 a connected to the pipe 12 in a communicating state. The tubular section 24 has a cylindrical shape. The shape of the tubular section 24 is not limited to the cylindrical shape, and may be a rectangular cylindrical shape.

The container section 25 includes a spherical shape, and has an open first opening 25 a and an open second opening 25 b. The container section 25 has a first opening 25 a connected to the other end portion 24 b of the tubular section 24 in a communicating state. The volume (the volume of the container section 25 when the first opening 25 a and the second opening 25 b of the container section 25 are closed) of the container section 25 is larger than the volume of the space inside the tubular section 24.

The shape of the container section 25 is not limited to a spherical shape, and need only have the volume larger than the volume of the tubular section 24. For example, the container section 25 may have a barrel shape having a diameter larger than a diameter of the tubular section 24. The bellows pipe 21 is connected to the second opening 25 b of the container section 25.

The acoustic device 13E according to the present embodiment functions as a Helmholtz resonator in which air inside the container section 25 serves as a spring.

According to the above embodiment, the volume V of the container section 25 of the acoustic device 13E can be adjusted, whereby the acoustic impedance of the pipe 12 can be adjusted.

The embodiments of the invention are described in detail with reference to the drawings, however, the specific configuration is not limited to the above embodiments, and includes a design change or the like without departing from the scope of the invention.

INDUSTRIAL APPLICABILITY

According to the invention, by attaching the acoustic device to the pipe, it is possible to reduce noise due to resonance of an acoustic eigenvalue of the space in the pipe with the NZ sound of at least one component of the compressor, the condenser, the expander, the evaporator, and the pipe that configure the chiller. The bellows pipe configuring the acoustic device expands to convert the acoustic energy into the structural vibration energy, whereby it is possible to reduce the size of the acoustic device.

REFERENCE SIGNS LIST

-   -   1: chiller     -   2: compressor     -   3: condenser     -   4: first expansion valve     -   5: second expansion valve     -   6: economizer     -   7: evaporator     -   8: inflow path     -   9: hot gas bypass pipe     -   10: hot gas bypass valve     -   11: refrigeration cycle     -   12: pipe     -   13, 13B, 13C, 13D, 13E: acoustic device     -   14, 14B, 14C, 14E: space formation section     -   15: porous plate     -   16: main body section     -   17: lid section     -   18: flange section     -   19: through-hole     -   20: sealing section     -   21: bellows pipe     -   21C: second bellows pipe     -   23: sealing section     -   23 a: cylindrical section     -   23 b: disc section     -   24: tubular section     -   25: container section     -   S: space     -   W: refrigerant 

1. A chiller comprising: a refrigeration cycle including a compressor, a condenser, an expander, an evaporator, a pipe that sequentially connects the compressor, the condenser, the expander, and the evaporator, and a discharge pipe; and an acoustic device provided in the pipe, wherein the acoustic device includes a space formation section in which a space is formed and which has an open first end connected to the pipe in a communicating state, a bellows pipe that is connected to an open second end of the space formation section and is extendable and contractable, and a sealing section that is provided in an end portion of the bellows pipe on a side opposite to the space formation section.
 2. The chiller according to claim 1, wherein the space formation section includes a first tubular section having a cylindrical shape, a second tubular section having a cylindrical shape, and a second bellows pipe connecting the first tubular section to the second tubular section, the first end is an end portion of the first tubular section on a side opposite to the second bellows pipe, and the second end is an end portion of the second tubular section on a side opposite to the second bellows pipe.
 3. The chiller according to claim 1, wherein the space formation section includes a tubular section that has one end portion connected to the pipe in a communicating state, and a container section that has an open first opening connected to the other end portion of the tubular section in a communicating state and has a volume larger than a volume of the space in the tubular section, and the bellows pipe is connected to an open second opening of the container section.
 4. The chiller according to claim 1, wherein the acoustic device includes a porous plate disposed at a boundary between the space formation section and a flow path of the pipe.
 5. The chiller according to claim 2, wherein the acoustic device includes a porous plate disposed at a boundary between the space formation section and a flow path of the pipe.
 6. The chiller according to claim 3, wherein the acoustic device includes a porous plate disposed at a boundary between the space formation section and a flow path of the pipe. 